Planigale tenwirostris, 1928

Russell A. Mittermeier & Don E. Wilson, 2015, Dasyuridae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 232-348 : 329-330

51.

Narrow-nosed Planigale

Planigale tenwirostris

French: Planigale a nez étroit / German: Spitznasen-Flachkopfbeutelmaus / Spanish: Planigalo de hocico estrecho

Taxonomy. Planigale tenuirostris Troughton, 1928,

“collected at Bourke or Wilcannia , New South Wales,” Australia.

E. Le G. Troughton in 1928 erected the genus Planigale to accommodate three species of tiny, flatheaded dasyurids known from Australia. In 1976, M. Archer conducted a revision of the genus Planigale and recognized three morphologically based species groups: the P. maculata group, containing P. maculata and P. novaeguineae, the P. ingrami group, containing P. ingramiand P. tenuirostris , which were similar morphologically; and a monotypic group containing P. gilesi , a species morphologically distinct from other planigales in several features, most notably in possessing only two upper and two lower premolar teeth. Various genetic studies have been conducted on the genus Planigale since the early 1980s. The genus was initially placed in its own subfamily because it shared no morphological features allying it undisputedly with other dasyurids. Nevertheless, Planigale was later incorporated in a distinct tribe, the Planigalini, within the subfamily Sminthopsinae , along with three other dasyurid genera (Smanthopsis, Antechinomys , and Ningaui ) based on genetics and serology. Monophyly of Planigale has been well established genetically. Using mtDNA, one study resolved P. tenuirostris as clearly divergent, monophyletic, and positioned as sister to a clade containing P. maculata and P. novaguineae. There does not appear to be any overlap in distribution between P. tenuirostris and P. gilesi in South Australia; their distributions are divided by a series of large lakes and the Strzelecki, Tirari, and Simpson deserts.

Monotypic.

Distribution. E Australia, in a broad zone encompassing SE Northern Territory, S & W Queensland, C & W New South Wales, and C & NE South Australia.

Descriptive notes. Head-body 5.7-5 cm (males) and 5-7 cm (females), tail 5.2-6.5 cm (males) and 5-6 cm (females); weight 4-5-9 g (males) and 4-7 g (females). There is mild sexual dimorphism for size. Like other planigales, the Narrow-nosed Planigale has a flattened triangular head, beady eyes, and pointed nose; ears are small, rounded, and lie against head. Narrow-nosed Planigales are russet brown above and off-white below. They have silky fur and a thin tail, which is almost as long as head-body length. Claws are caramel in color. There are three upper and lower premolar teeth. Compared with congeners, the Narrow-nosed Planigale is most similar to the Long-tailed Planigale ( P. ingrami ); indeed, they differ in few characters. One study found that only hindfoot length (larger in the Narrow-nosed Planigale) and supratragus of the ear (larger in the Long-tailed Planigale) were significantly different. Body weights of adult South Australian specimens showed Narrow-nosed Planigales (mean = 5-5 g, range = 3-1-8, n = 39) to be significantly heavier than the Long-tailed Planigales (mean =4-6 g, range = 3-5-5-5, n = 14). Skull of the Narrow-nosed Planigale was less flattened and cranial region slightly more domed than those of the Long-tailed Planigale. Rostrum and nasal bones were narrower in the Narrow-nosed Planigale than in the Long-tailed Planigale. Auditory bullae of the Narrow-nosed Planigale were short, and frontals usually had extremely minute postorbital processes. Size of incisors and premolars also differed between the two species: incisors (except for upper and lower I1) and premolars were typically larger in the Narrow-nosed Planigale than in the Long-tailed Planigale.

Habitat. Cracking clay soils, including open grassy areas, low shrub and woodland (mallee) scrubs, and densely vegetated flats beside creeks. In some soils, cracks that Narrow-nosed Planigales inhabit may be only 30 cm deep, and in others, cracks extend an impressive 2 m deep. One study focused on determining distribution of the Narrow-nosed Planigale in the arid interior in eastern Australia. It was most strongly associated with stony plains, medium clay soils, and low shrubland and tussock grassland. The Narrow-nosed Planigale was recorded at only three sites that represent regularly flooded habitats supporting Eucalyptus coolabah ( Myrtaceae ) and Muehlenbeckia florulenta ( Polygonaceae ). Most captures of Narrow-nosed Planigales were at sites holding water for only short periods, such as cottonbush ( Maireana aphylla) low shrublands and typical gibber (desert pavement) plain low-shrub communities that included oodnadatta bush ( Atriplex nummularia omissa), bladder saltbush ( Atriplex vesicaria), and samphire (7 Tecticornia medullosa = Sclerostegia medullosa), all Amaranthaceae . Some Narrownosed Planigales were collected from herb lands and tussock grasslands with cracking clay soils. In the southern Flinders Ranges, it was recorded in Eucalyptus goniocalyx and E. leucoxylon heathy woodland and mallee communities. On ridges and slopes of the northern Flinders Range, arid spinifex (7riodia spp., Poaceae ) hummock grasslands provided suitable habitat for the Narrow-nosed Planigale. Most of these sites had some areas with cracking clay-loamy soils. One study assessed habitat use by Narrow-nosed Planigales, Gile’s Planigales ( P. gilesi ), and Fat-tailed Dunnarts ( Sminthopsis crassicaudata ) in the arid zone of New South Wales. All three species showed considerable flexibility in habitat use at all times, and abundance was poorly predicted from easily measured parameters of habitat. Nevertheless, evidence suggested that these three species were separated based on microhabitat. Plant height was positively associated with abundance of the Narrow-nosed Planigale, and it was the only good predictor for this species.

Food and Feeding. The Narrow-nosed Planigale is an agile climber, hunting beetles, grasshoppers, spiders, crickets, and moths among soil cracks, grass, and shrubs. The Narrow-nosed Planigale pushesits narrow, flattened head like a wedge into litter, pressing apart grass stems and turning over leaves in search of hidden arthropod prey. It wrigglesits silky, loose-skinned, and flexible body into narrow fissures and spaces. The Narrow-nosed Planigale is a fearless predator; it will use its forepaws to efficiently attack and kill a grasshopper or centipede larger than itself, repeatedly biting the prey’s head and body until it is subdued. While eating, the Narrow-nosed Planigale sometimes sits on its hindlegs using forepaws to hold larger pieces of food. It does not need to drink, getting sufficient moisture from its juicy prey.

Breeding. Studies indicate that breeding in the Narrow-nosed Planigale begins in late July or early August and continues until mid-January. Females are polyestrous, having an estrus cycle of 33 days; litters are born 19 days after mating. Although females have 10-12 teats in the pouch, average litter size is only six. Pink, hairless young are just 3 mm long at birth and remain continuously attached to teats until they are c.40 days old when they detach themselves. At this time, the mother builds a nest in which young are left so she can forage alone for food. Eyes of young are open at 51 days. They suckle until development is complete at c.95 days, and then they become independent. It is possible for a female to raise two litters in a season, but probably few do so in the wild. In captivity, some individuals reach three years of age, but in the wild,it is unlikely that more than 15% of the population survives to more than two years old. In one study of a captive population, male Narrow-nosed Planigales tended to grow faster than females. Eye opening and weaning were two important developmental stages, associated with reduced growth rates; changes in juvenile body condition indicated that the mother initiated weaning.

Activity patterns. The Narrow-nosed Planigale is primarily nocturnal. In summer,it can be active any time of night; in winter,it is most active in the three hours after sunset and the four hours preceding dawn. Activity occurs mostly in short bursts of less than five minutes, followed by rest for a minute or so. More than 70% of nocturnal activity is below ground where individuals scurry over vertical sides of cracks. Hindlegs of Narrow-nosed Planigales have remarkable flexibility and rotate at hip and anklejoints, allowing flattening of the body to get into tight places. In somesoils, cracks inhabited may be only 30 cm deep, in others, more than 2 m; these cracks provide essential shelter from heat in summer and cold in winter. Winter nighttime temperatures above ground can fall below zero, but itis a much cozier 10-13°C in the cracks below ground.

Movements, Home range and Social organization. During the breeding season, male Narrow-nosed Planigales make short “tsst, tsst” calls, perhaps to contact potential mates; females utter similar calls but only during estrus. On average, each individual rests or sleeps for more than 21 hours/day, alone or in a group. Especially in winter, several individuals huddle together in a nest of dried grass and littered with discarded remnants of prey. Huddling reduces loss of body heat and helps conserve energy. The Narrow-nosed Planigale also reduces energy use by entering daily torpor, during which metabolism is reduced by 30-50%. Basking in the sun reduces energy loss during winter; individuals may perch near the top of a crack to get sun. Narrow-nosed Planigales have no clearly defined territories or home ranges. Areas of occupancy shift continuously during the year, probably in response to seasonal and yearly fluctuations in prey abundance. Densities of Narrow-nosed Planigales are low and vary considerably from year to year and within a year. Even in optimum habitat, densities of the Narrow-nosed Planigale are likely less than 1 ind/ha. Because Narrow-nosed Planigales spend a lot of time in deep soil cracks, it is difficult to obtain movement data, but in one study, 27 males moved an average of 172 m (range 0-600 m), and eight females moved an average of 100 m (range 5-550 m) over the two year study period.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Narrow-nosed Planigale has a wide distribution, presumably has a large overall population, occurs in a number of protected areas, and does not face any major conservation threats. The Narrow-nosed Planigale is locally common when habitat contains a hectare or more of cracking clay. Populations fluctuate with rainfall; there have been declines in the eastern part of its distribution due to habitat transformation.

Bibliography. Archer (1976a, 1982c), Baverstock et al. (1982), Blacket, Adams et al. (2000), Blacket, Kemper & Brandle (2008), Ellis, van Weenen & Burnett (2008), Krajewski, Blacket et al. (1997), Krajewski, Young et al. (1997), Painter et al. (1995), Read (1984a, 1984b, 1985, 1987a, 1987b, 1987c, 1988, 1989, 2008b), Troughton (1928).

Figures

On following pages: 41. Short-furred Dasyure (Murexia longicaudata); 42. Broad-striped Dasyure (Murexia rothschildi); 43. Long-nosed Dasyure (Murexia naso); 44. Red-tailed Phascogale (Phascogale calura); 45. Northern Brush-tailed Phascogale (Phascogale pirata); 46. Common Brush-tailed Phascogale (Phascogale tapoatafa); 47. Giles's Planigale (Planigale giles); 48. Long-tailed Planigale (Planigale ingrami); 49. Common Planigale (Planigale maculata); 50. Papuan Planigale (Planigale novaeguineae); 51. Narrow-nosed Planigale (Planigale tenuirostris); 52. Wongai Ningaui (Ningauiride); 53. Pilbara Ningaui (Ningaui timealeyi); 54. Southern Ningaui (Ningaui yvonneae); 55. Kultarr (Antechinomys laniger).

Distribution. E Australia, in a broad zone encompassing SE Northern Territory, S & W Queensland, C & W New South Wales, and C & NE South Australia.